This invention relates to planographic printing and provides a method of preparing a planographic printing member and a planographic printing member per se. The invention relates particularly, although not exclusively, to lithographic printing.
Lithographic processes involve establishing image (printing) and non-image (non-printing) areas on a substrate, substantially on a common plane. When such processes are used in printing industries, non-image areas and image areas are arranged to have different affinities for printing ink. For example, non-image areas may be generally hydrophilic or oleophobic and image areas may be oleophilic. In "wet" lithographic printing, a dampening or fountain (water-based) liquid is applied initially to a plate prior to application of ink so that it adheres to the non-image areas and repels oil based inks therefrom. In "dry" printing, ink is repelled from non-image areas due to their release property.
There are numerous known processes for creating image and non-image areas. Recently, much work has been directed towards processes which use laser imaging, in view of the ease with which lasers can be controlled digitally.